A Bronx dad pleaded not guilty today to charges he drowned his son and fed his daughter rat poison after their mother dumped him for another man.

Leonardo Espinal, 47, allegedly went berserk after being dumped by the mother of his kids, Rosaura Abreu, venting his rage on Stewart, 5, and Mia, 7, prosecutors charge.

Espinal drowned Stewart in a bathtub at his stepmother’s home before later feeding his daughter pizza spiked with deadly rat poison in November. In a half hearted suicide attempt, Espinal ate some of the rat poison before he was arrested.

His daughter survived and lives with her mom.

Currently at Riker’s Island, Espinal requested and received protective custody from Judge Harold Adler during his appearance in Bronx Supreme Court yesterday.

He blew a kiss to his teary-eyed daughter in law and his adult son from a previous relationship before leaving court.

Espinal’s next appearance is scheduled for Feb. 1, when the results of a full psychological evaluation are expected.